The present invention relates to a machine for making tea bags for infusion in liquid.
The invention relates in particular to a tea bag making machine which uses a process whereby an infusable product, in loose form, is measured and fed into a filter bag consisting of folded sheets of porous material, heat-sealed to each other and equipped with a thread for holding the filter bag during infusion. The machine relates in particular to the making of filter bags containing tea or chamomile without thereby restricting the scope of the disclosure but including also herbs and any other products capable of being infused in a liquid.
In the tea and chamomile filter bag sector, it is very important that the thread be fastened to the filter bag very securely to prevent it from coming loose when the filter bag is immersed in the infusion liquid.
Indeed, stirring and agitating the tea bag during infusion, for example with a teaspoon, in order to speed up the infusion process is such a widespread tendency that tea bag manufacturers in some countries must conform with technical standards that specify a minimum limit of resistance to detachment of the filter bag from the thread, below which filter bags are considered unacceptable because they cannot provide consumers with a sufficient guarantee of not coming loose during infusion.
In the case of filter bags made by heat-sealing, one known solution envisages the formation of a small portion of loop with one end of the thread, the portion of loop being held between the overlaid, heat-sealed edge flaps of the sheets of porous material and fixed to them by two short sections impregnated with the adhesive with which the edge flaps are heat-sealed to each other.
This solution, although simple in construction, does not provide a sufficient guarantee of meeting the minimum requirement of resistance to detachment enabling the thread to remain securely fixed to the filter bag during infusion.
The present invention has for an object to provide a machine for making tea bags capable of solving the problem mentioned above.